Study On The Sliding Construction Method Of Space Truss With Unequal Height Long-span In Nanchang Station

Because of its good integrity,high strength and light weight,long-span grid structure has been widely used in large public buildings in recent years,the lower concrete structure of upper grid is the most common form of grid structure.And as the most commonly used construction technology of Long-span Grid Structure in China,The diversity of construction methods and the complexity of internal forces of sliding method cause the complexity of internal force distribution of construction structure and the force variability of final formed structure.Therefore,in order to ensure the construction safety and smooth progress,It is necessary to analyze the cooperative work of the upper and lower parts of the grid structure starting from the initial design of the project to obtain the working state index of the whole structure and to control the deformation of the quasi-structure in the construction stage;study the construction technology used in the project,point out the problems existing in the construction process structure,and carry out the simulation analysis of the whole construction process to understand the mechanical characteristics of the construction stage and find out the possible safety problems in the construction process.According to the simulation calculation of the whole structure,the working state index is obtained,and the mechanical behavior of the whole process of grid installation is calculated by using the Midas/Gen finite element analysis software;the stability of the over-limit frame construction is verified and the sliding synchronism of the frame is simulated;Combined with the time-varying mechanics of construction,the deformation of quasi-structure in construction stage is controlled,and the construction technology is studied,and the problems in construction process are pointed out:1.Considering that the superstructure and the lower concrete column work together,the whole structure model is different from the independent grid structure model in support reaction force,the member internal force,the element stress distribution,the structure displacement,the time history analysis and so on.And the overall calculation results are more than the separate calculation results,so it is necessary to carry out the overall calculation analysis for this kind of mixed structure;the introduction of series spring model can more truly reflect the actual working state of the support;2.The tread frame Sliding construction method is selected as the construction method of this project,which verifies the overall stability of the tread frame structureunder the condition of exceeding the limit,determines the tread frame sliding mode,and uses the finite element analysis software to simulate the overall stability and synchronous control difficulty of the one-point and multi-point traction in the tread slip process;3.Two kinds of grid construction methods which can be used in this project are given: the traditional method and the back top method,the construction technology of the two construction methods is introduced,and the simulation analysis of the whole construction process is carried out by using the finite element analysis software.the conclusion that the back top method is superior in terms of stability and safety is obtained,in addition to the disadvantages of long construction period,.